Drum rotors are well known in the gas turbine engine industry. See, e.g., commonly assigned U.S. Pat. Nos. 4,426,191 to Brodell et al and 4,483,054 to Ledwith. Most drum rotors have a spacer or knife edge labyrinth seal between adjacent rotor stages (disks).
The components of the prior art drum rotors (i.e., the disks and seals) are fabricated from the same alloy; drum rotors used in some gas turbine engines are made of high strength superalloys, such as IN100. Nonetheless, they may become damaged or worn during service use. The knife edge seals are typically thin wall structures, and are relatively fragile; as a result, they are especially prone to damage and wear. Once damaged or worn, these seals must be repaired if further use of the drum rotor is desired. However, superalloys like IN100 have a tendency to crack when repaired using known weld repair techniques, such as those shown in U.S. Pat. No. 4,159,410 to Cooper. This factor significantly complicates the repair of the knife edges. The inability to readily weld repair the knife edges, therefore, complicates the use of drum rotors made from such high strength superalloys. Accordingly, engineers have sought to define improved materials and fabrication techniques which will produce drum rotors made of high strength superalloy materials and are weld repairable.